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[Clinical significance of the estimations of complement and immune complexes]
Insights
Immune complexes (IC) and complement (C) interactions cause tissue damage. Measuring serum levels of total hemolytic activity (CH 50) and IC is vital for diagnosing and managing diseases like SLE, with new methods improving IC assessment.
Area of Science:
- Immunology
- Biochemistry
Context:
- Immune complexes (IC) interacting with complement (C) are implicated in tissue injuries.
- Sequential serum level estimations of IC and C components are clinically significant for disease monitoring.
Purpose:
- To highlight the clinical utility of total hemolytic activity (CH 50) in diagnosing and managing Systemic Lupus Erythematosus (SLE).
- To discuss the diagnostic challenges and potential of novel methods for immune complex estimation in various diseases.
Summary:
- Total hemolytic activity (CH 50) is a key complement parameter for SLE diagnosis and treatment. While elevated CH 50 is nonspecific, decreased levels indicate various conditions, notably chronic liver disease, necessitating liver function assessment.
- Current immune complex (IC) estimation methods have variable sensitivity and specificity, limiting their clinical significance to diseases like SLE. Recent advancements using monoclonal antibodies and rheumatoid factors may enhance IC assessment.
- Proper sample handling is crucial; heat-inactivation of serum below 56°C can affect IgG reactivity with rheumatoid factors, thus serum should be analyzed without heat-inactivation.
Impact:
- Improved understanding of the role of complement and immune complexes in disease pathogenesis.
- Potential for enhanced diagnostic accuracy and personalized treatment strategies for immune-mediated diseases.
- Guidance on optimal laboratory practices for accurate immune complex and complement analysis.
Abstract:
Immune complexes (IC) interacting with complement (C) induce tissue injuries and the estimations of their sequential serum levels is clinically significant. In C, among the various parameters, total hemolytic activity (CH 50) is clinically the most useful especially in the diagnosis and treatment of SLE. Elevation of serum CH 50 levels is nonspecifically observed in patients with inflammations and malignancies, although its mechanism remain obscure. Decreased CH 50 levels were observed in various diseases including liver diseases, collagen diseases, kidney diseases, congenital C component deficiencies and so on. Among them, chronic liver disease is the most frequently encountered disease. Liver function should be checked first in cases with low CH 50. In IC, patho-etiological significance has been established and various methods for the estimation have been employed. However, their sensitivities and specificities are various and positivities obtained by these methods vary with the diseases. Clinical significance of IC estimation has been recognized to be limited to a few diseases including SLE, in which some clinical signs parallel the IC level. However, recent developments in the methods employing murine monoclonal antibodies to C1q and C3d and IgG rheumatoid factor are expected to help re-evaluation the significance of serum IC estimation in various diseases. Heat-pretreatment of sera at 56 degrees C or below produced the reactivity of IgG with rheumatoid factors. Therefore, serum samples should be estimated without heat-inactivation.